1. Field of the Invention
The present invention relates to a memory system including a memory card, and more particularly to a memory system in which a nonvolatile semiconductor memory is mounted. Further, the present invention relates to a memory system controller mounted in a memory system and a data processing method in a host apparatus.
2. Description of the Related Art
A memory card, e.g., an SD™ memory card, is used as a storage medium of a host apparatus such as a personal computer. Of such memory cards, there is a memory card in which an error correction circuit (an ECC circuit) is mounted (see, e.g., Jpn. Pat. Appin. KOKAI Publication No. 2000-173289, p. 4, FIG. 1).
The error correction circuit generates code data which is an error correction code based on write target data at the timing of writing the data. Further, the error correction circuit reads read target data as well as code data corresponding to this data at the time of reading the data. Furthermore, the error correction circuit performs error correction processing with respect to the read target data based on this read code data. In this manner, the conventional memory card improves reliability of storage data by mounting the error correction circuit therein.
The error correction circuit mounted in a host apparatus may have an error correction capability superior to that of the error correction circuit mounted in a memory card in some cases. In such a case, performing error correction processing by the error correction circuit in the host apparatus can correct more error bits than that in case of performing error correction processing by the error correction circuit in the memory card.
However, in the conventional memory card, when an uncorrectable data error is detected by the error correction circuit in the memory card during a data read operation, this data is not output. Therefore, even if an error can be corrected by the error correction circuit in the host apparatus but cannot be corrected by the error correction circuit in the memory card, the error cannot be corrected.